The present invention relates to a cutting insert for chip removing machining, the cutting insert comprising an elongate center part, cutting edges being arranged at the opposite ends of the center part, and the cutting insert being provided with engagement members along two longitudinal, opposite sides, the cutting edges, in an end view of the cutting insert, forming a mutual angle. The present invention also relates to a tool, which comprises a cutting insert according to the present invention.
A cutting insert for chip removing machining is previously known through EP 0 416 854 B2, especially for axial turning of circular grooves. The cutting insert is received in a holder and has cutting edges in opposite ends. The cutting insert has a generally elongate shape and both the cutting edges are arranged on a longitudinal side. The cutting insert has grooves on opposite longitudinal sides and these grooves co-operate with ridges of the holder. The groove that is situated on the same side as the cutting edges is situated between the cutting edges. The cutting edges and the deepest part of the appurtenant groove are essentially situated at the same distance from the groove on the opposite side.
An additional cutting insert for chip removing machining is previously known through U.S. Pat. No. 6,648,560, the cutting edges provided at the opposite ends of the cutting insert being twisted 90° in relation to each other. By such an arrangement, the cutting edge that is inactive is twisted away in such a way that it is situated inside the groove that the active cutting edge generates. Still another cutting insert for chip removing machining is previously known through U.S. Pat. No. 5,836,723 showing cutting edges in one embodiment facing in opposite vertical directions.
It is desirable to provide a cutting insert of the kind defined by way of introduction, wherein the cutting insert can work in greater cutting depths than the total length thereof without a trailing cutting edge contacting the piece to be machined.
It is also desirable that the cutting insert according to the present invention should give a lower insert cost than cutting inserts having only one cutting edge.
It is still further desirable to increase the stability of the fastening of the cutting insert in the holder.
In a cutting insert for chip removing machining according to an aspect of the present invention, the cutting insert comprises an elongate center part, cutting edges being arranged at the opposite ends of the center part, the cutting insert being provided with engagement members along two longitudinal, opposite sides, the cutting edges forming, in an end view of the cutting insert, a mutual angle (α), wherein rake faces associated with the respective cutting edge are facing opposite directions in the vertical direction of the cutting insert, and the angle (α) between the cutting edges is in the interval of 10°<α<20°, a distance (H1) being measured between the intersection of the cutting edge with a center line (C1-C1) of the cutting insert and the outermost portion of the lower engagement member and in that in an end view of the cutting insert, the ratio between the distance (H1) and the height (H) of the cutting insert is the following: 0.5H≦H1≦0.7H, the distance (H1) and the height being measured along a center line (C1-C1) of the cutting insert.
In a tool for chip removing machining according to another aspect of the present invention, the tool comprises a disc-shaped holder as well as a cutting insert received in the holder, the cutting insert comprising an elongate center part, cutting edges being arranged at the opposite ends of the center part, the cutting insert being provided with engagement members along two longitudinal, opposite sides, the cutting edges forming, in an end view of the cutting insert, a mutual angle (α), wherein the rake faces associated with the respective cutting edge are facing the opposite direction in the vertical direction of the cutting insert, the angle (α) between the cutting edges is in the interval of 10°<α<20°, a distance (H1) being measured between the intersection of the cutting edge with a center line (C1-C1) of the cutting insert and the outermost portion of the lower engagement member and in an end view of the cutting insert the ratio between the distance (H1) and the height (H) of the cutting insert is the following: 0.5H≦H1≦0.7H, the distance (H1) and the height being measured along a center line (C-C) of the cutting insert.